Heat shield

ABSTRACT

The present invention relates to a heat shield for shielding of hot areas of a part. Such heat shields are for instance used for shielding hot areas of combustion engines, especially of catalysts, exhaust manifolds, turbo chargers and the like or also in the conditioning of batteries. Conventionally, they comprise at least one metallic sheet layer. In addition to this metal sheet layer, which renders stability to the heat shield, typically an insulating layer made of insulating material, e.g. porous material is provided as a further layer.

The present invention relates to a heat shield for shielding of hot areas of a part. Such heat shields are for instance used for shielding hot areas of combustion engines, especially of catalysts, exhaust manifolds, turbo chargers and the like or also in the conditioning of batteries. Conventionally, they comprise at least one metallic sheet layer. In addition to this metal sheet layer, which renders stability to the heat shield, typically an insulating layer made of insulating material, e.g. porous material is provided as a further layer.

As far as the insulating layer is not embedded between the two metal sheets, the insulating layer is applied with its entire surface to the part to be shielded so that it rests to the latter.

The operation of combustion engines and the like are subject to variations in load, which results in a varying heat production over the operation time. It is for instance necessary to heat up the combustion engine immediately after its cold start to high temperatures, in order to keep emissions and consumption at a minimum. To this end, an insulation is provided which prevents the heat radiation and convection of the hot or heating part to the widest extent. On the other hand, when the combustion engine reaches its full load operating condition, it is necessary to provide for a heat radiation or convection as high as possible in order to prevent the hot part or its elements from overheating. This is of particular importance if these parts are not durable against high temperatures.

Given the priority of the protection against overheating for the shielded part and of the durability of the heat shield itself, it is often necessary in the heat shield arrangements according to the state of the art, to design them in such a manner that the emission reduction at cold starting cannot be considered at all or only to a small extent. However, with newer vehicles, especially also with hybrid vehicles, operational conditions with partial load and operational phases with frequent new starts predominate. For this reason, it is important to consider these operational conditions to a larger extent in the design.

This is the starting point of the present invention, which objects on providing a heat shield with which an excellent insulation can be achieved in all operational conditions but at the same time allows for a sufficient heat removal at high heat load. The present invention also relates to a component assembly with a heat-emitting part, which is arranged at a heat shield according to the present invention.

This object is solved by a heat shield according to claim 1 and the component assembly according to claim 19. Advantageous embodiments of the heat shield according to the invention are given in the dependent claims.

The present invention solves the problems described above by providing a heat shield for shielding of hot areas of a part, which comprises at least one metallic layer. Adjacent to this metallic layer, a further insulating layer is arranged which extends in the plane of the layer essentially parallel to the metallic layer. Thus, the insulating layer extends between the part to be shielded and the metallic layer. Both of these layers preferably follow the outer shape of the part to be shielded. The insulating layer consists of porous insulating material or comprises such. Advantageously, on the surface of the insulating layer which faces away from the metallic layer, no further layers are arranged or only layers which are formed according to the contour of the insulating layer, so that the insulating layer comes to rest on the hot part directly or indirectly. The insulating layer on its surface which faces away from the metallic layer comprises at least one flow channel. The flow channel is formed as a groove into the surface of the insulating layer.

If the insulating layer with its entire surface—the one surface pointing towards the hot part—rests on the hot part, the hot part together with the walls of the groove delimits the flow channels in the insulating layer. At high temperatures of the hot part, convection between the hot part and the insulating layer takes place through these flow channels, which guides the heat between the hot part and the insulating layer to the outside, especially if the part shows a high temperature.

Thus, the flow channels according to the invention are directly integrated into the porous insulating material. As they are formed as grooves which are closed when the heat shield comes to rest on the hot part and thereby build up the flow channels, it becomes possible to introduce the flow channels in a simple manner into the insulating layer. With the heat shield according to the invention, it is advantageous that for instance with a cold part, the convection between this part and the heat shield is small and therefore only little heat is discharged. If the part has however reached a high temperature, an increased heat removal takes place via the integrated flow channels of the heat shield.

With regard to a most simplified manufacturing and fastening of the heat shield, it is preferred if it consists in several partial shells, which are connected to each other to form a heat shield which annularly surrounds the part. It is especially advantageous if the heat shield is constructed from two half-shells which each consists in a metallic layer on their outside and an insulating layer on their inside. It is however also possible to combine a larger number of partial shells to an annularly closed heat shield. It is particularly preferred if the housing formed by the partial shells is closed in such a manner that at least a part of the flow channels at the interface, at which the housing is closed, pass over in a flush manner. The partial shells are for instance connected to each other after having been mounted around the part. In this case, connection is in particular performed at the collar-shaped protrusions which are provided in all partial shells at their edge regions. In the same way, it is possible to install the partial shells individually. In a further advantageous embodiment, at least two half-shells are connected to each other via a kind of hinge, so that the heat shield can be mounted as a whole. The hinges used in this context can be separately produced parts via which the partial shells are connected to each other. It is however also possible, that the heat shield comprises bending areas which are provided as integral structure in the metallic layer of the heat shield. In this case, the partial shells directly cohere with each other and therefore are no separate parts.

It is preferred if at least one of the flow channels comprises at least one device for active or passive opening and closing or ventilation. In advantageous embodiments, the flow channels at their entrances and outlets can have a closing and opening function and this way can be switched on or off. This enables a control of the surface temperature of the hot part. To this end, one advantageously uses a control circuit with a temperature sensor, e.g. at the hot part or at the heat shield, especially at its surface. In order to control the flow channels, it is also possible to use actuators or thermo-sensitive materials which are able to close or open the channels due to their temperature-controlled agility. An opening of the channels has to be ascertained especially under full load conditions in order to achieve an improved heat removal.

The passage of gas or air through the flow channels is either achieved in a passive manner using natural convection or in case of an engine of a vehicle or additionally using the slip stream or by an active blowing of the gases, e.g. using a fan. It is further possible to condition the gas in advance. To this end, it can be heated using an electrical heating or using phase change materials. As an alternative, it can be cooled using the air condition of the vehicle prior to passing through the channels of the heat shield.

Advantageously, the insulating material consists in a fleece, which is for instance reinforced with a ceramic binder. Such a fleece can be molded to a preform. It is also possible to simultaneously mold the flow channels into the surface of the fleece which faces away from the metallic layer. If desired, an additional surface treatment can be provided for, e.g. using a ceramic-based high-temperature adhesive or a ceramic-based high-temperature coating or lacquer, in order to reinforce the surface of the insulation layer by forming a kind of skin. Such high-temperature adhesive, coatings and lacquers can for instance be materials, which at temperatures between 150° C. and 250° C. tend to form a skin.

As insulation materials, glass mats, especially made from SiO₂, Al₂O₃ and/or CaO with a binder; expanded mica, basalt rock wool, all kinds of ceramic masses, expanded clay or high-temperatures such as polyimide or melamine are suited. Sandwich constructions, especially with at least one of the materials mentioned before are possible, too.

Formation and arrangement of the flow channels can be done in different manners, which have to be adapted to the thermal needs, which may be assessed using thermography of the hot part to be shielded. In this respect, the flow channels have to be adapted to the requirements in removal of heat in the hot part and in cases also to the need of heat removal in particular areas of the hot part, the so-called hot spots. The flow channels can show various patterns on the surface of the insulating layer, e.g. along the longitudinal extension of the heat shield or also transverse to it, helical in the shape of a one-level thread or a two-level winding and/or in the shape of several flow channels which are oriented in counter flow relative to each other. In most cases, it is preferable if the heat shield does not comprise a single flow channel only but that at least two flow channels are formed in the insulating layer which channels surround the part independent of each other. The distances of the flow channels can be adapted to the respective need in heat removal. Thus, they may be arranged closer to each other in the area of hot spots. The cross sections of the flow channels may be constant over their course or can be varied along their course with respect to their height and/or width, resulting in an adaptation to the local requirements. The total length of the flow channels, the pattern of the flow channels, a possible pooling of several flow channels at their inlet or outlet to a single channel and the like can be adapted to the respective requirements. It is especially advantageous if the channels in the partial shells are formed flush to each other, so that the flow of the gas is realized all around the entire part. If only such channels are given which extend in the longitudinal extension direction of the heat shield, this is of course not required.

Especially in areas of a hot spot, it can be advantageous to enlarge the width of a channel extending in this area, and preferably to simultaneously reduce its height. With this, the contact area between gas and part is increased and the heat transfer to the gas and the heat removal are improved. The cross section of the flow channels can in particular in the area of hot spots can also considerably vary in the flow direction of the gas, showing varying cross sections, so that the gas experiences turbulences, which improves the heat transfer to the gas.

To improve cooling performance and to homologize the outside thermal map of the entire heat shield, it can be advantageous to provide at least a first winding on the hot side of the insulating layer (as already described) and a at least a second winding on the outer surface of the insulating layer resulting at least in a first cooling circuit on the inner surface of the insulating layer and at least a second cooling circuit on the outer surface of the insulating layer. This enables to run the first and second cooling circuits in different directions or in the same direction. The first cooling circuits can run in parallel to the second cooling circuits, thus without shift relative to the plane of the surface of the insulating layer or be staggered. Further, they can extend relative to each other like a double helix or in a manner crossing each other in a projection into the middle of the insulating layer at several places. It is particularly preferred if the airflow passes the second cooling circuit(s) resulting from the second winding(s) on the outer surface of the insulating layer, as this guarantees for a simple and permanent cooling during operation of the vehicle while no cooling takes place during rest phases of the vehicle which facilitates the warm-up. Using first and second cooling circuits on the inner and outer surface of the insulating layer allows for further opportunities in designing the thermal map according to the requirements of each special operation condition.

Instead of forming the at least one first winding on the inner surface of an insulating layer and the at least one second winding on the outer surface of the same insulating layer, it is also possible to achieve a comparable design using a sequence of at least three insulating layers, the inner one with recesses for the at least one first winding, the second one being continuous and the outer one with recesses for the at least one second winding.

Cross sections with an area of 10 to 500 mm², advantageously of 30 to 200 mm² are particularly suited for the flow channels. The distances between individual flow channels can advantageously range between 5 and 100 mm, further advantageously between 10 and 50 mm.

In case of flow channels arranged in a thread-like manner, which continue over several partial shells, their slope can be between 25 and 100 mm, in particular about 50 mm. The width of the channel advantageously ranges between 3 and 30 mm, more advantageously between 4 and 20 mm and most advantageously between 8 and 12 mm. For the channel height, 2 to 20 mm, advantageously 5 to 15 mm and more advantageously 5 to 10 mm are especially suited.

The cross sectional shape of the flow channels can vary as well and be adapted to the actual requirements, e.g. by use of a semi-circular, rectangular or a trapezoidal cross section. In case of a trapezoidal cross-section, the longer basic side can either be arranged on the side of the hot part or opposite to it. Omega-shaped cross sections are possible, too. The arrangement of the flow channels along the hot part is especially preferred, as this results in a good cooling. However, an inclined orientation, at an angle of between 5 and 45°, advantageously about 20° relative to the longitudinal direction of the part is suited, too. In a preferred embodiment, the groove forming a flow channel at least on a section of its longitudinal extension can show a cross section that tapers, advantageously tapers in a conical manner. Further, this cross section can taper and widen in sections along the groove.

It is not necessary that the insulating layer shows the same extension as the at least one metallic layer. Rather, edge areas may be free of insulating material especially if they only aim on the fixation of the heat shield via its metallic layer to the hot part. However, it is preferred that the insulating extends over at least 50%, preferably at least 80%, preferably at least 90% of the planar extension of the metallic layer.

The at least one metallic layer comprises or consists in a steel sheet, in particular a stainless-steel sheet, an aluminated steel sheet, in particular a fire-aluminated steel sheet and/or an aluminum-plated steel sheet or the like. The metal sheet can have the form of a smooth metal sheet or it can be dimpled at least in sections. It is most preferred that the outer surface of the at least one metallic layer has a good reflectivity. As a consequence, the heat shield according to the invention combines reflection, convection and insulating properties and allows for a tailored design to the particular application.

The heat shield according to the invention is used for shielding of hot parts, in particular of parts of an internal combustion engine, especially in vehicles, thus mainly in passenger cars and utility vehicles. The heat shield is thus particular suitable for applications in the exhaust line, in particular at the exhaust manifold or for the unit for exhaust treatment, the unit for supercharging as well as for heat exchangers, for instance heat exchangers for the heating of transmission oil, in the additional heating for the passenger room and/or in the battery conditioning.

In the following, some examples of heat shields according to the invention are given. In all these examples the same or similar reference numbers are used for identical or similar elements, so that their repetition may be avoided. In the following examples, several elements according to the invention are represented in combination with an example. Each of these elements according to the invention can however also represent an advantageous embodiment of the present invention independent of the other elements of the respective example.

It is shown in

FIG. 1: A heat shield according to the state of the art;

FIG. 2: A heat shield according to the invention comprised of two partial shells;

FIGS. 3 and 4: Top-views of heat shields according to the invention;

FIGS. 5 to 7: Examples for the orientation of flow channels according to the present invention;

FIG. 8: A heat shield according to the invention with a hinge mechanism; and

FIG. 9: A further example for the orientation of flow channels according to the present invention.

FIG. 1 shows a heat shield 1 with an outer metal layer 2. An insulating layer 3 consisting in a porous material is arranged essentially parallel to the metal sheet layer 2. The insulating layer 3 is embedded into the metal layer 2 and reinforced by the latter. The metal layer 2 consists in fire-aluminated stainless steel, the insulating layer 3 in a glass-fiber mat free of binder. The metal sheet layer 2 and the insulating layer 3 in their geometry follow the geometry of the two adjoining parts and this way show a three-dimensional form with convexities, e.g. in the areas 40. The heat shield 1 according to FIG. 1 in practice is combined with a second half-shell and corresponds to the state of the art.

FIG. 2 schematically represents the construction of the heat shield 1 from two half shells 1 a and 1 b in an exploded view. Both the half shells are provided for encircling a catalyst 9 as the adjacent part in a circular manner. The half shells themselves consist in an aluminized, or stainless steel shell 2 a, 2 b, into which an insulating layer 3 a, 3 b has been inserted each. Other than the insulating layers in the state of the art, the insulating layers 3 a, 3 b consist in a glass fiber mat which has been fixed with a ceramic binder, so that the half shells keep their shape permanently. This is especially required for the durable stability of the channels 10, which pervade the insulating layer on its surface pointing towards the part 9.

In FIG. 3, a half-shell of a heat shield 1 similar to the one in FIG. 1 but according to the invention is shown in a top view to the surface facing the hot part. As corresponds to the invention, here on the surface of the heat shield 1 pointing towards the hot part, grooves 10 a to 10 d are molded into the insulation layer 3, through which gas can flow between the hot part and the insulating layer 3. To this end, the grooves 10 a to 10 d between their ends reach to the end of the insulating layer 3 and therefore each comprise and inlet 5 a to 5 d and an outlet 6 a to 6 d. The grooves 10 a to 10 d in the installed state continue in the complementary half-shell that is not shown here. The grooves 10 a to 10 d show an essentially half-circular cross section, with a maximum depth of the grooves of 8 mm and a maximum width of the grooves being 10 mm.

In FIG. 4, a half-shell of a heat shield according to the invention is shown in a top-view to the surface pointing towards the hot part. Here, the insulating layer 3 is marked with an undulating hatching. Again, the flow channels are molded as grooves 10 a to 10 g into the surface of the insulating layer, which faces the hot part, the flow channels crossing the insulating layer up to its edge. The edges 8 of the metallic layer 2 in several areas of the border region towards the second half-shell protrude collar-shaped to the outward and this way form a resting area for corresponding collar-shaped protruding edges of the second half-shell. The collar-shaped protruding edges to this end may comprise passage openings for fastening means for the connection of the two half-shells, these passage openings not being depicted in detail here. As an alternative, the complementary edges can also be fixed to each other by clamping or plugging connections.

FIG. 5 in partial figures A to D shows several possibilities for the arrangement of the flow channels 10 a to 10 d on and within the surface of an insulating layer 3. In FIG. 5A a total of four flow channels 10 a to 10 d which extend under an angle of about 120° relative to the longitudinal axis of the hot part are given. These channels surround the part and this way form a single continuous channel. This follows from the corresponding cross-sectional drawing in FIG. 5B, where the partial shells are combined in a schematic drawing. FIG. 5B is a simplified drawing which does not reflect that the channel sections 10 a to 10 d do not extend in parallel to the plane of the paper, but as a helical channel inclined to the latter, as follows from FIG. 5A. Accordingly, the inlet and the outlet of the channel are situated in front of and behind the plane of the paper.

FIG. 5C also shows channels 10 a, 10 b, 10 c, and lad which helically surround a hot part or to be more precise their sections, here again, multi-layered helixes are given. Although the channels 10 a to 10 d extend in parallel to each other, the gases flowing in channels 10 a and 10 c here flow in the opposite direction to the gases flowing in channels 10 b and 10 d.

In FIG. 5D, an arrangement of two flow channels 10 a and 10 b, which helically surround a hot part is shown. These are staggered relative to each other, so that the convolutions of the two flow channels 10 a and 10 b are extending in an alternatingly nested manner. The two flow channels are arranged in such a way that their passage is effected in a cross-flow.

In partial Figures A to C, FIG. 6 shows the arrangement of flow channels in parallel to the longitudinal axes of a hot part. FIG. 6A here shows a detail from the insulating layer 3, where four flow channels 10 a to 10 d which are arranged in parallel to each other and which extend in a straight way can be identified.

In FIG. 6B, a cross section through an arrangement of parts is depicted which corresponds to the one in FIG. 6A. The channels 10 a to 10 d in their longitudinal direction, thus the direction orthogonal to the drawing plane in FIG. 5B, extend in parallel to each other. In FIG. 6B, one can realize that apart from channels 10 a to 10 d, further channels are given and that the heat shield 1 completely encircles the hot part 9 and this way insulates and cools the latter.

In FIG. 6C, an arrangement of flow channels 10 a to 10 e is shown, which to a large degree corresponds to the one in FIGS. 6A and 6B, but where the channels 10 a to 10 e extend under an angle of about 20° to the longitudinal axis of the hot part 9, which longitudinal axis extends horizontally in FIG. 6C.

In FIG. 7, too, a corresponding section of an insulating layer 3 is shown, where the flow channels 10 a to 10 h extend under an angle to the longitudinal axes of the hot part, which longitudinal axis extends horizontally. In addition, the cross section of the flow channels 10 a to 10 h compared to each other is neither identical nor constant. In particular, the cross section of the flow channels 10 c to 10 f is smaller than the one of channels 10 a, 10 b and 10 g. Further, the distance of channels 10 c to 10 f to each other is smaller and therefore, the density of channels in this area is higher than for the channels 10 a, 10 b, 10 g and 10 h. Such an arrangement and design of the flow channels can for instance be chosen in the area of a hot spot of the hot part to be shielded with the hot spot being covered by the channels 10 c to 10 f. With this, a better cool-down of the hot spot can be achieved, as in the area of the hot spot, the flow velocity in the channels 10 c to 10 f is high and further, the density of the channels is increased.

FIG. 8 illustrates a further embodiment of a heat shield according to the invention. As in FIG. 2, the heat shield 1 consists in two half-shells 1 a, 1 b, which here are however connected to each other via a hinge 7. The half-shells 10 a, 10 b, as already described beforehand, each consist in an outer, metallic layer 2 a, 2 b and an inner, insulating layer 3 a, 3 b. The ratio between the thickness of the metal sheet layer 2 a, 2 b and of the respective insulating layers, 3 a and 3 b are not to scale. In the insulating layer 3 a, 3 b semi-circularly profiled channels 10 a to 10 d extend, which in a helical manner continue into or out of the paper plane. When the two half-shells 1 a, 1 b of the heat shield 1 are closed around the part to be shielded 9 using the hinge 7, the ends of the channels 10 a, 10 b in half-shell 1 a find their continuation in the other half-shell 1 b which cannot be identified here, and this way form a continuous helix. The protruding edges 8 of the two half-shells 2 a, 2 b upon closure at least in sections come to rest in a facial way on each other and can be connected using fasting means, e.g. clips or screws.

FIG. 9 shows a simplified cross section through an assembly comprising a part to be shielded, and a heat shield arranged immediately on this part, now in a further embodiment of the invention. Here, the insulating layer 3 is not one-piece but consists of three essentially concentrical layers 3, 3′ 3″, which in this order rest one on the other. Both the innermost layer 3 and the outermost layer 3″ comprise flow channels for air, namely channels 10 a to 10 d in the outermost layer 3″being delimited by the metallic layer 2 and channels 10 a′ to 10 10 d′ in the innermost layer delimited by the part 9. The way the simplified cross section has been set up corresponds to the one used for FIG. 5B. Thus, it is a simplified drawing which does not reflect that the channel sections 10 a to 10 d and 10 a′ to 10 d′, respectively, do not extend in parallel to the plane of the paper, but as helical channels inclined to the latter. Accordingly, the inlet and the outlet of the respective channels are situated in front of and behind the plane of the paper. The arrows in FIG. 9 indicate that in the innermost layer 3, the air in the channels 10 a′ to 10 d′ flow in the clockwise direction when flowing from the spectator into the paper plane, while the channels 10 a to 10 d in the outermost layer 3″ in the same perspective flow in an anti-clockwise direction. This allows for an influence of one channel to the other. If the air flowing in the channels 10 a to 10 d in the outermost layer 3″ is airflow, this allows for an extremely efficient cooling of the air in the inner channels, without negative impact on the warm-up. As an alternative to the inverse rotational sense of the two groups of channels with the channels being shifted to each other shown here, in the outermost and the innermost layer, an identical flow direction and/or a parallel arrangement are possible as well. While from a production perspective it is advantageous to design a heat shield according to the invention with an insulating layer with channels on its inner surface and its outer surface from several layers of insulating material, it can be formed from a single layer, too. 

1-19. (canceled)
 20. A heat shield for shielding of hot areas of a part with at least one metallic layer and an insulating layer having a porous insulating material arranged at least in sections adjacent to the metallic layer, comprising: at least one flow channel formed into the porous insulating material of the insulating layer on its surface pointing away from the metallic layer, the channel extends as a groove on the surface of the insulating layer which points away from the metallic layer.
 21. The heat shield of claim 20, wherein the insulating layer extends over at least 90% of the planar extension of the metallic layer.
 22. The heat shield of claim 20, wherein the heat shield is comprised of several partial shells, which in the installed state encircle the part in an annularly closed manner.
 23. The heat shield of claim 20, wherein the metallic layer is a sheet selected from the group consisting of a stainless-steel sheet, a fire-aluminated steel sheet, and an aluminum-plated steel sheet.
 24. The heat shield of claim 20, wherein the insulating material is a fleece that has been reinforced with a ceramic binder or a fleece that is moulded to a shaped part.
 25. The heat shield of claim 20, wherein the insulating material is selected from the group consisting of a glass fiber fleece, an expanded mica wool, a basalt rock wool, a ceramic mass, an expanded clay, a high-temperature foam, and combinations of the foregoing in layers of different materials.
 26. The heat shield of claim 20, wherein the insulating layer at least in areas is surface-treated to achieve a reinforced surface, the surface treatment selected from a group consisting of a ceramic-based high-temperature adhesive, coating with a ceramic-based high-temperature lacquer, impregnating with a material and treating by compression under elevated temperature.
 27. The heat shield of claim 20, wherein one or several flow channels are formed in the surface of the insulating layer in such a way that they extend distanced to each other.
 28. The heat shield of claim 27, wherein the distance between individual sections of a flow channel and/or the distance of several flow channels relative to each other in areas with a higher thermal load of the heat shield is smaller than in areas with a smaller thermal load.
 29. The heat shield of claim 20, wherein a housing has a laminar self-contained hollow shape to take up the hot areas.
 30. The heat shield of claim 20, wherein one or several of the flow channels are distanced to each other and encircle the hollow space at least once in a surrounding manner.
 31. The heat shield of claim 29, wherein the housing is closed so that at least a part of the flow channels at an interface, at which the housing is closed, pass over in a flush manner.
 32. The heat shield of claim 20, wherein at least two flow channels are formed which surround the part independent of each other.
 33. The heat shield of claim 20, wherein at least one flow channel is helically disposed about the part and shows a varying distance between convolutions of the helix with respect to the main direction of the helix.
 34. The heat shield of claim 20, wherein the groove forming one flow channel at least on a section of its longitudinal extension shows a cross-section selected from the group consisting of rectangular, quadratic, trapezoidal and semi-circular.
 35. The heat shield of claim 20, wherein the groove forming a flow channel at least on a section of its longitudinal extension shows a cross section that tapers in a conical manner and/or that shows a cross section which along the groove in sections tapers and in sections widens.
 36. The heat shield of claim 20, wherein the heat shield further comprises at least one device for an active or passive closing and/or ventilation of at least one of the flow channels.
 37. The heat shield of claim 20, wherein the heat shield shields parts of an internal combustion engine, selected from the group consisting of an exhaust manifold, a unit for exhaust treatment, a unit for the supercharging of heat exchangers, a unit for the heating of transmission oil, a unit for heating of the passenger room, and a unit for the battery conditioning.
 38. The heat shield of claim 20, wherein the heat shield is arranged at the part so that the insulating layer with its surface pointing away from its metallic layer at least in sections rests on the surface of the part and in these areas the surface of the part together with the grooves of the flow channels at least in sections forms the flow path for a fluid or delimits such.
 39. The heat shield of claim 20, wherein the groove extends from one end of the insulating material, across the insulating material to a second end of the insulating material.
 40. The heat shield of claim 20, wherein the channel is located on the surface of the insulating material so the channel directly faces the part to be shielded.
 41. The heat shield of claim 20, wherein the metallic layer is a sheet selected from the group consisting of a smooth metal sheet and a steel sheet that is dimpled at least in sections. 